Orthodonella apohamatus, Lin & Gong & Song, 2004

Lin, Xiaofeng, Gong, Jun & Song, Weibo, 2004, Morphological studies on a new species of Orthodonella, with redescription of O. gutta (Cohn, 1866) Kahl, 1931 (Protozoa: Ciliophora: Synhymeniida) from coastal water off Qingdao, China, Journal of Natural History 38 (16), pp. 2001-2011 : 2002-2006

Class KINETOFRAGMINOPHORA de Puytorac et al., 1974 Order SYNHYMENIIDA de Puytorac et al., 1974 Family ORTHODONELLIDAE Jankowski, 1968 Genus Orthodonella Bhatia, 1936 Orthodonella apohamatus nov. spec. ( figures 1, 2, 4, 8, 9 , 20–28 ; table 1)

Diagnosis

Marine Orthodonella in vivo 60–160 6 20–35 M m; lanceolate body shape with conspicuous beak-like projection at anterior end; 42–60 (mean 53) somatic kineties, including 28–42 on ventral and 13–20 on dorsal side; synhymenium with about 54–62 dikinetids; pharyngeal basket composed of 8–13 rods; four contractile vacuoles, two in middle near left margin and two at posterior end of cell; one elongated macronucleus and one micronucleus.

Type location and ecological characters

This species was found once in large numbers in clean littoral water off Qingdao. Salinity was about 31, pH 8.0, water temperature 16 ‡ C.

Type specimens

One holotype, a slide of protargol-impregnated specimens, is deposited in the Natural History Museum , London, UK with registration number 2003:3:27:3; one

paratype (No. Lin-02-05-30) is deposited in the Laboratory of Protozoology, Ocean University of China.

Description

Cell size highly variable, 60–160 6 20–35 M m in vivo (N ~6). Body generally acontractile and constant in shape though it might be conspicuously different among individuals: from slender, spindle-shaped to broadly enlongated ( figure 4 ); basically lanceolate in outline, anterior portion always strongly bending to left with beak-like projection, posterior end conspicuously narrowed to widely pointed ( figures 1, 4 , 20–22, 25 ). Dorsoventrally flattened about 3:1. Somatic cilia densely arranged, about 5–8 M m in length. Cytostome (Cyst) rounded ( figure 9 ), in anterior

Data are based on protargol-impregnated specimens. All measurements are in M m. Mean, arithmetic mean; CV, coefficient of variation; N, sample size.

quarter near right margin ( figure 2 , double-arrowheads; figures 20–22 , arrows). Nematodesmata conspicuous, about 22 M m long, consisting of 8–13 pharyngeal rods and forming funnel-shaped basket ( figure 24 , arrow). Cytoplasm colourless, often containing many greasy globules (3–4 M m across). Food vacuoles usually with diatoms, which often render the specimens rather brownish at low magnification ( figures 1 , 20, 25 ). Four contractile vacuoles (CV; 3–6 M m across; N ~6) distributed in two groups: two in middle near left margin, another two near posterior end of cell ( figures 1, 9 ). Macronucleus (Ma) elongated, about 10–40 6 4–13 M m in size after impregnations ( figures 2, 4, 8 ), containing densely packed globular nucleoli. Single micronucleus (Mi) oval in shape, about 8 M m long, close to macronucleus ( figures 2, 8 , 23 , arrow).

Movement slow, gliding on substratum without pause.

Infraciliature as shown in figures 8, 9 , 26–28 . Synhymenium positioned obliquely from right margin to apical end of beak, in which about 54–62 dikinetids are closely packed ( figures 2, 9 , 26 , arrows). In total 42–60 (mean 53) somatic kineties including about 36 (28–42) on ventral, which terminate anteriorly at the synhymenium: preorally about six rows curving around cytostome and separated by it ( figure 9 , arrowheads); postorally meridional. On dorsal side, about 13–20 (mean 16) kineties, which are less densely distributed than those on ventral side ( figures 8, 9 ).

Figures

FIGS. 1–11. Morphology and infraciliature of Orthodonella apohamatus nov. spec. (1, 2, 4, 8, 9) and O. gutta (3, 5–7, 10, 11) from life (1, 3, 5–7) and after protargol impregnation (2, 4, 8, 9–11). (1) Ventral view of a typical individual. (2) Ventral view, to show the synhymenium (arrows) and nuclear apparatus. (3) To demonstrate the form-transfiguration of the same individual. (4) To show different body shapes and sizes among individuals. (5) Cortical granules. (6) Oil globules. (7) Ventral view of an extended individual. (8, 9) Dorsal and ventral view of the same specimen, to show the general infraciliature, arrow indicates the synhymenium and arrowheads show the ‘broken’ kineties. (10, 11) Dorsal and ventral view of the same specimen, to show the general infraciliature, arrow indicates the synhymenium and arrowheads show the ‘broken’ kineties. CV, contractile vacuole; Cyst, cytostome; Ma, macronucleus; Mi, micronucleus. Scale bars: 40 Mm.

FIGS. 20–28. Photomicrographs of Orthodonella apohamatus nov. spec. from life (20–22, 25) and after protargol impregnation (23, 24, 26–28). (20) Ventral view of a typical individual, arrow marks the cytostome. (21, 22, 25) To show the form-transfiguration among different individuals, arrows show the cytostome. (23) To show the macronucleus and micronucleus (arrow). (24) To indicate the pharyngeal rods (arrow). (26–28) To show the infraciliature, arrow indicates the synhymenium. Scale bars: 40 Mm.